Absorption refrigeration



Oct. 13, 1953 W G, KOGEL ABSORPTION REFRIGERATION 2 Sheets-Sheet l FiledJuly 14, 1949 Oct. 13, 1953 W G, KQGEL 2,655,010

ABSORPTION REFRIGERATION Filed July 14, 1949 2 Sheets-Sheet 2 O A 5a.

Patented Oct. 13, 1953 UNITED STATES PATENT GFFICE ABSORPTIONREFRIGERATION Application July 14, 1949, Serial No. 104,771 In SwedenJuly 22, 1948 13 Claims. (Cl. (i2-119.5)

This invention relates to refrigeration and is especially concerned withrefrigeration systems of the absorption type and refrigerators embodyingsuch systems or apparatus.

The objects of this invention are to provide an improved refrigerationsystem of this type having a new arrangement and relationship of partsor members which not only contribute to a compact apparatus or unit butalso provide for efficient heat exchange between fluids circulating inthe system and insure reliable operation under all operating conditionsencountered in practice; to provide in such a system an arrangement inwhich one component or member forms a unitary or integral part of one orseveral other members; to combine several components or members in oneunitary or integral part whereby eiiicient heat exchange may be effectedbetween fluids circulating in the system; to provide such a unitary orintegral part in the circuit for circulation of rerigerant which servesas a pressure vessel for inert gas and is in good thermal relation withthe inert gas circuit to promote use of such vessel as an extension ofthe condenser; to provide such a pressure vessel which is advantageouslyutilized to conduct refrigerant therefrom to an evaporator; to provide anew relationship of parts in the circuit for absorption liquid in whicheiiicient heat exchange between fluids in such circuit is promoted andat the same time loss of heat from such fluids to the surroundings isminimized; to provide an improvement for varying the quantity ofrefrigerant fluid actively circulating in the system; to provide animproved arrangement for raising liquid refrigerant from a condenser toa higher level, as to the evaporator, for example, whereby reliablelifting or pumping of such refrigerant is always assured; and to providea unitary and compact condenser and absorber construction wherebyeflicient air cooling of such parts by natural draft circulation iseffected.

The novel features which are believed to be characteristic of theinvention are set forth with particularity in the claims. The invention,both as to organization and method, together with the above and otherobjects and advantages thereof, will be better understood by referenceto the following description taken in conjunction with the accompanyingdrawings forming a part of this specification, and of which:

Fig. 1 illustrates more or less diagrammatically an absorptionrefrigeration system of the inert gas type embodying the invention;

Figs. 2 to 5 are fragmentary Views diagrammatically illustratingmodiiications of the system shown in Fig. 1; and

Fig. 6 is an elevation View of a refrigeration system like that shown inFig. l diagrammatically illustrating another embodiment of theinvention, the system being fixed to framework adapted to be mounted ina refrigerator cabinet.

In Fig. 1 the invention is shown embodied in an absorption refrigerationsystem of a type employing an inert gas or pressure equalizing agent.Systems of this type are well known and include a generator or vaporexpulsion unit I0, a condenser I I, an evaporator I2 and absorber I 4which are connected to one another to provide circuits for circulationof refrigerant fluid, inert gas and absorption liquid. By way ofexample, ammonia may be employed as the refrigerant, hydrogen as theinert gas and water as the liquid absorbent.

The vapor expulsion unit I0, which is enveloped within a body 9 ofsuitable insulating material, may comprise a boiler I5 in the form ofpiping to which heat is supplied from a heating tube or iiue I6thermally connected therewith at Il, as by welding, for example. Theheating tube I0 may be heated in any suitable manner, as by anelectrical heating element disposed within the lower part of the tube I6or by a liquid or gaseous fuel burner which is adapted to project itsllame into the lower end of the tube.

The heat supplied to the boiler I5 and its contents expels refrigerantvapor out of solution, and the refrigerant vapor passes through arectifier I8 into the air cooled condenser II in which it is condensedand liqueed. In a manner to be described hereinafter, liquid refrigerantis conducted from condenser I I to evaporator I2 in a path of ow whichincludes conduits I9 and 20, the evaporator being diagrammatically shownand arranged to eiiect cooling of a thermally insulated space 2l. Inevaporator I2 liquid refrigerant evaporates and diffuses into an inertpressure equalizing gas, such as hydrogen, which enters through aconduit 22. Due to evaporation of refrigerant uid into inert gas inevaporator l2, a refrigerating effect is produced with consequentabsorption of heat from the surroundings.

The rich gas mixture of refrigerant vapor and inert gas formed inevaporator I2 flows from the lower part thereof through one passage 23of a gas heat exchanger 24 and conduits 2E and 26 into the lower end ofthe absorber I4 which is in the form of a looped coil. In the absorberI4 the rich gas mixture ows countercurrent to downwardly iiowingabsorption liquid which enters through a conduit 2l. The absorptionliquid absorbs refrigerant vapor from inert gas, and inert gas Weak inrefrigerant flows from the upper end of absorber I4 through a conduit28, an-

other passage 29 of gas heat exchanger 24 and conduit 22 into the upperpart of evaporator I2. In Fig. 1 the evaporator I2 is connected in theinert gas circuit just described in such manner that parallel flow ofinert gas and refrigerant fluid is effected in the evaporator. However,it should be understood that the evaporator I2 may be connected in thegas circuit in any other desired manner so that, for example, inert gasand refrigerant fluid pass in counterflow with respect to one another.

The circulation of gas in the gas circuit just described is due to thedifference in specific weight of the columns of gas rich and weak,respectively, in refrigerant vapor. Since the column of gas rich inrefrigerant vapor Iand flowing from evaporator I2 to absorber I4 isheavier than the column of gas weak in refrigerant and flowing fromabsorber I4 to evaporator I2, a force is produced or developed withinthe system for causing circulation of inert gas in the manner justdescribed.

In a manner to be described hereinafter, absorption solution enriched inrefrigerant fiows from the lower part of the absorber I4 through aconduit 30 into the upper part of boiler I5. From the lower closed endof boiler I5 absorption solution passes into the lower end of avertically extending tube 3I in which liquid is raised by vapor-liftaction, the tube 3| being heat conductively connected to the heatingtube I6, as by welding, to effect such lifting of liquid. The raisedliquid passes from the upper end of tube 3I into the upper part of astandpipe or riser 32, and, as will be described presently, absorptionliquid weak in refrigerant flows from the lower part thereof to theabsorber I4 in a path of flow which includes conduit 21.

The standpipe or riser 32 may or may not be heat conductively connectedto the heating tube I5. The principal part of generated vapor producedin the vapor expulsion unit I is expelled from solution in boiler I5,and liquid of decreasing refrigerant concentration flows downwardlytoward the bottom end thereof into the vaporlift tube SI. A liquidcolumn is maintained in the standppe 32 whose liquid surface is at sucha level that absorption liquid weak in refrigerant can flow by gravityfrom the lower end of the standpipe into the upper part of the absorberthrough the conduit 21.

The vapor passing from the upper end of vapor lift tube 3| into thevapor space of standpipe 32 flows therefrom through a downwardlyextending conduit 33 into the lower end of a horizontally extending pipesection I 5a formed at the upper part of boiler I5. The pipe section I5ayconstitutes an analyzer into which passes vapor generated in the boilerI5 and in the vapor lift tube 3I. The generated Vapor usually is amixture of refrigerant vapor and absorption liquid vapor. When ammoniais employed as the refrigerant and water as the absorbent, for example,the generated vapor usually is a mixture of ammonia vapor and watervapor. Due to the difference in boiling points of ammonia and water,water vapor may be removed from ammonia vapor by cooling the mixture tocondense out the water.

In Fig. 1 vapor generated in the boiler pipe I5 passes upwardlytherefrom through the pipe section I5a, and vapor generated in tube 3Ialso enters such pipe section through conduit 33. The absorption liquidintroduced into the pipe sec.-

tion or analyzer I5a is relatively rich in refrigerant and at a lowertemperature than the generated vapor, and in bubbling through theenriched absorption solution at least a part of the water vapor iscooled suiciently and condenses, thus removing water vapor from ammoniavapor. The latent heat of condensation resulting from condensation ofwater Vapor is given up to the enriched absorption solution and forms aninternally heated zone in which some ammonia vapor is expelled out ofsolution. Such refrigeration vapor mixes with refrigerant vaporgenerated in the vapor lift tube 3l and boiler I5, and the mixturepasses from the analyzer I5a to the rectier I8.

In the rectifier I8, which may be provided with internal baflies 34,further cooling of generated vapor is effected which is sufficient tocause condensation of water vapor and thereby effect its removal fromammonia vapor. -Such condensate drains downwardly in the rectifier I8and mixes with enriched absorption solution flowing to the boiler I5.The latent heat of condensation resulting from rectification ofgenerated vapor, that is, condensation of water vapor, is usuallyreferred to as heat of rectification.

In accordance with this invention liquid refrigerant formed in condenserII is raised therefrom to a higher level in such manner that positiveraising or lifting of refrigerant liquid is assured under all operatingconditions encountered, particularly when the system is placed inoperation following a shut down period. In the embodiment of Fig. 1 thisis accomplished by providing a conduit or vessel to an intermeiateportion of which the outlet end 36 of the condenser II is connected.

Liquid refrigerant formed in condenser I I flows therefrom into vessel35 and accumulates in the lower part thereof. From vessel 35 liquidrefrigerant flows through conduit I9 into the lower part of verticallyextending conduit 20 which is heat conductively connected with therectifier I8 at 31, as by welding, for example. Due to heat ofrectification supplied from the rectifier I8, liquid refrigerant israised by vapor lift action through conduit 20 to an air cooledcondenser 38 which may be provided with a plurality of heat dissipatingmembers 39.

The vapor formed in the lower part of conduit 20 for raising liquidtherethrough passes from the upper end of such conduit into condenser 38and is condensed and liquefied therein. The raised liquid refrigerantand refrigerant condensed in condenser 38 ilows through a conduit 40into the upper part of evaporator I2 for gravity flow through thelatter, as previously explained.

If desired, the condenser 38 may be omitted and an arrangement providedin which the lifting vapor passing from the upper end 0f conduit 20 isreturned to the vessel 35 which essentially serves as an extension ofcondenser II and in which returned vapor is condensed. Such amodification is shown in Fig. 2 in which the upper end of conduit 20 isconnected to the upper part of the vertical leg 4I of a generally U-shaped liquid trap 42 whose horizontally extending leg 43 is connectedat the outer end thereof by a conduit 44 to the upper end of evaporatorI2. When liquid refrigerant in liquid trap 42 reaches the level at whichconduit 44 is connected thereto, liquid refrigerant overflows throughsuch conduit into evaporator I2 for gravity flow through the latter. Theconduit 20 is connected to leg 4I at a level above the connection ofconduit 44 to leg 43, that is, the Vapor space of leg 4I, and liftingvapor passes from such vapor space through a conduit t5 to the vessel3'5 in which the vapor is condensed and liquefied.

The heat conductive connection 3'! between conduit 20 and rectifier I3extends for a sulficient distance lengthwise of these members to insuresuch transfer of heat of rectification to conduit 20 that vaporizationof liquid refrigerant will occur in the latter to insure lifting ofrefrigerant by vapor lift action. The conduit or lift tube 20 is thusheated to a definite temperature, depending upon the boiling point ofsubstantially pure refrigerant under conditions prevailing in thesystem, to cause vaporization of such refrigerant or refrigerant havinga relatively small concentration of liquid absorbent.

The diameter of conduit 20 is sufficiently small so that the vaporbubbles formed due to heat transfer in this manner cannot freely passliquid in conduit 20, thereby effecting lifting of liquid by vapor liftaction. Such lifting of liquid is accomplished under the influence ofthe column of liquid in vessel 35 whose liquid surface level may be atthe level indicated at t6 in Fig. 1, for example, such liquid columnusually being referred to as a reaction head which over-balances thecolumn of vapor bubbles and liquid slugs therebetween being raised inconduit 20.

Vaporization of liquid refrigerant in conduit 20 by heat of recticationtakes place at a relatively loW temperature. tion of or quantity ofabsorption liquid present in liquid cooling agent or refrigerant inconduit 20 becomes too high, vaporization of such liquid by heat ofrectification often cannot take place at such relatively low temperature'oecause the presence of liquid absorbent increases the boilingtemperature, that is, the temperature at which vaporization occurs. Thisis especially true when the conduit or vessel 35 contains liquid whichis essentially liquid absorbent and which may occur, for example, whenthe i most adverse operating conditions encountered, n

particularly when the refrigeration system is being started, provisionis made for removing liquid absorbent from the liquid lifting systemformed by vessel 35 and conduits i9 and 25. In the embodiment of Fig. lthis is accomplished by providing a conduit 41 whose lower endcommunicates with the conduit I9 and lower end of conduit 2!! and whoseupper end is preferably connected to rectifier I8 at a level which issubstantially at or slightly above the liquid surface level of theliquid column maintained in vessel 35 during operation of the system,such liquid column constituting the reaction head for pumping or raisingliquid refrigerant, as previously explained.

If it is assumed the liquid lifting system contains liquid which isessentially or for the most part liquid absorbent when the refrigerationsystem is started following a shut down period, the vessel 35 willcontain such liquid absorbent. Under these conditions liquid refrigeranthaving a relatively small concentration of liquid absorbent will beformed in condenser Il and flow therefrom into vessel 35 and graduallyset- When the concentrag;

tle over the body of liquid absorbent. In this way liquid absorbent invessel 35 will be displaced from the latter and pass through conduits I9and 4'! into the rectifier I8. Eventually all of the liquid absorbent invessel 35 and conduit I9, as well as the liquid absorbent in conduit 20,will be replaced by liquid refrigerant having a relatively smallconcentration of liquid absorbent, thereby enabling conduit 20 tofunction and cause lifting of liquid refrigerant therethrough by vaporlift action by heat of rectication, as previously explained. The liquidabsorbent entering rectifier I8 from the upper end of conduit 41 flowsdownwardly by gravity and finds its Way to the absorption liquidcircuit.

In view of the foregoing, it will now be understood that positive andreliable lifting or pumping of liquid refrigerant from condenser I I toa higher level can always be effected, even under the most adverseoperating conditions encountered, by removing liquid absorbent from theliquid lift or pump system. In Fig. 3 as illustrated another manner ofremoving liquid absorbent from the liquid lifting system which isespecially effective in promoting rapid lifting of liquid refrigerantfrom condenser II to a higher level. The embodiment of Fig. 3 differsfrom that of Fig. 1 in that conduit 41 is replaced by a conduit i3 whichis more or less U- shaped to form a liquid trap having one leg 49communicating with the conduit 20 at approximately the liquid level 46in vessel 35 and the other leg 50 communicating with the rectifier I8 atthe same level or possibly slightly higher level.

The connections of conduit 48 to the conduit 2Q and rcctier I5 may beaccomplished by forming small openings 5I and 52 in the latter, andsecuring the upper open ends of legs 49 and 5@ to the conduit 25 andrectifier I8, respectively, at regions surrounding such openings. Inaddition, conduit i3 is formed of relatively small or narrow tubing todevelop a definite resistance to passage of liquid even before the U-shaped trap formed by this conduit is completely filled with liquid. Inthe event the liquid lifting system of Fig. 3 contains liquid absorbent,such absorbent is replaced by liquid refrigerant having a relativelysmall concentration of absorbent substantially in the saine manner as inthe embodiment of Fig. l and described above. However, in Fig. 3 liquidabsorbent is displaced from vessel l35 and forced through conduit I9 andlower part of lift tube or conduit 20 into the U-shaped conduit 48. Fromconduit 48 such liquid absorbent passes into rectifier IB, andultimately conduit 2i) will contain liquid refrigerant having arelatively small concentration of absorbent, so that lift tube 25 willeffectively function to raise such liquid therethrough.

In accord with the invention the embodiment of Fig. 1 embodiesprovisions for varying the quantity of refrigerant fluid circulating inthe refrigeration system for producing useful refrigeration. This isaccomplished by providing a vessel 53 in which refrigerant fluid is heldin an inactive portion of the refrigeration system under certainoperating conditions. The vessel 53, which may be referred to as aconcentration vessel, is connected to receive liquid refrigerant in thelower part thereof through a conduit 54 whose upper end is connected at55 to the conduit 25 immediately ahead of a barrier or dam 56 withrespect to the direction of flow of liquid from the evaporator I2.

In this manner unevaporated liquid refrigerant passing from the lowerend of evaporator I2 and flowing through the inner passage 23 of gasheat exchanger 24 is diverted by the dam or barrier 55 into conduit 54through which it is conducted to vessel 53 and collects therein. Thevessel 53 is heat conductively connected to rectifier I8 in any suitablemanner, as by welding, so that heat of rectification is transferred byrectifier I8 to vessel 53 and its contents. Vaporization of liquidrefrigerant continuously takes place in vessel 53 due to such heatingyand such vapor passes upwardly from the vessel through a connection 51into the extreme upper part of rectifier I8 and flows into the condenserI I along with vapor flowing from the rectifier into the condenser.

When the load on evaporator I2 increases less unevaporated refrigerantpasses from the lower end thereof; and, when the evaporator loadincreases sufficiently, all of the refrigerant supplied to theevaporator I2 evaporates and diffuses into inert gas therein to produceuseful refrigeration. Under such operating conditions the flow of liquidrefrigerant to vessel 53 through conduit 54 ceases; and, with continuedevaporation of liquid refrigerant in vessel 53 by heat transfer theretofrom rectifier I8, refrigerant vapor flows therefrom to condenser I Iuntil the vessel is depleted of liquid.

Hence, when the load on evaporator I2 increases, as when ice trayscontaining water to be frozen are positioned in an ice freezingcompartment of the thermally insulated space 2 I, for

example, a greater quantity of refrigerant fiuid actively circulates inthe refrigeration system to promote useful refrigeration and take careof increase in load. Conversely, when the load on the evaporator I2decreases and unevaporated refrigerant passes from the lower endthereof, such refrigerant fluid collects in vessel 53 when it owsthereto at a faster rate than that at which it evaporates due to heatingfrom the rectifier I8. While unevaporated refrigerant may be allowed todrain through a liquid trap in conduit 54 directly into the bottom partof vessel I and mix with refrigerant the-rein, it will be understoodfrom the foregoing that certain advantages are realized by providing theconcentration vessel 53 which functions in the manner just described.

The vessel 53 is connected in the system in such manner that removal ofliquid therefrom, even a mixture of liquid refrigerant and absorbent, isreadily effected without any additional provisions. Liquid absorbentpresent in vessel 53 is vaporized therein and the vapor thus formed,which is not required to lift liquid by vapor lift action, passes intocondenser Il from which it is drained into the absorption liquidcircuit, as previously described. Also, the refrigeration system may besuch that there is inadequate space in the system for storing andholding a large quantity of excess refrigerant. By providing the vessel53, such excess refrigerant is effectively withheld from circulation andreturned to the active portion of the system to produce usefulrefrigeration without the necessity of draining such refrigerant intothe absorption liquid circuit.

In absorption refrigeration systems of the inert gas type beingdescribed, it is usually the practice to provide a separate vessel whichis connected to the outlet end of the condenser and to the gas circuit,respectively, so that any inert gas which may pass through the condensercan fiow into the gas circuit. Refrgerant vapor not liquefied in the CLIcondenser flows into such separate vessel to displace inert gastherefrom and force such gas into the gas circuit. The effect of forcinggas into the gas circuit in this manner is to raise the total pressurein the entire system whereby an adequate condensing pressure is obtainedto insure condensation of refrigerant vapor in the condenser. For thisreason the separate vessel connected in the refrigeration system in themanner just described is usually referred to as a pressure vessel.

In further accord with the invention, in order to simplify therefrigeration system and provide a compact arrangement of components orparts, the vessel or conduit 35 is arranged to serve as a pressurevessel which surrounds or envelops the conduit 26 and forms a jacketabout the latter. The outlet end of condenser I I is connected to anintermediate part of pressure vessel 35, so that the lower part thereofserves as a place for holding liquid refrigerant flowing thereto fromthe condenser. Further, the upper part of conduit 26 is formed with anopening 58 to connect the pressure vessel 35 to a part of the gascircuit so that the latter will function in the manner described above.Therefore, as illustrated in Fig. l and just described, the vessel 35serving as the pressure vessel of the refrigeration system forms aunitary or integral part of at least one other member or component ofthe system. In the embodiment of Fig. 1 the vessel 35 and the manner inwhich it envelops conduit 26 actually makes the pressure vessel anintegral part of several members of the refrigeration system andeliminates connections previously necessary, especially the conduitconnections to such a pressure vessel when a separate vessel is employedfor such purpose.

By employing vessel 35 as a pressure vessel which envelops conduit 26,desirable heat exchange between fiuids in the system is effected,particularly to effect cooling and condensation of refrigerant in vessel35 which passes therein from condenser II. Since gas enriched inrefrigerant, which is relatively cold, ows through conduit 2G, it isdesirable to shield the latter thermally from atmospheric air to avoidcondensation of moisture at the outer surfaces thereof. In Fig. 1 thisis effectively accomplished by employing vessel 35 as a jacket aboutconduit 26. In order to shield all parts of the path of flow forrelatively cool enriched gas, the conduit 25 and adjacent ends of gasheat exchanger 24 and vessel 35 may be enveloped in a body 5819 ofsuitable insulating materlal, as shown in Fig. 4. Alternatively, the gasheat exchanger 24 and vessel 35 may be so formed and connected in therefrigeration system that adjacent ends of these members or componentsare in abutting relation at 59, as shown in Fig. 5, thereby completelyenveloping conduit 26 for the relatively cool rich gas. In thearrangement of Fig. '5, the conduit 28 through which gas Weak inrefrigerant flows from absorber I4 desirably is shifted to the outerextreme end of the gas heat exchanger 24.

It is usually the practice to mount the refrigeration system orapparatus on a wall of a household refrigerator cabinet, particularlythe rear Wall of such a cabinet, for example. In such case the lateralside Walls of the outer shell of the cabinet project rearwardly from therear insulated wall to form a vertically extending space for housingparts of the refrigeration apparatus. Such vertically extending spacemay be completely operi or closed or partly closed by a Wall member. Inany event the vertically extending similar parts are designated by thesame reference numerals. The vapor expulsion unit Illa of Fig. 6 isenveloped in a body 9a of suitable insulation and comprises a boiler Ibin the form of a vertical pipe having an upper extension whichconstitutes the rectier Ia having baffles 34a therein. Heat is suppliedto boiler lh from a heating tube I6a thermally connected therewith atIla, such heating tube being of a type adapted to be heated by anelectrical heating element therein. However, the heating tube may bearranged to extend entirely through the insulation body 9a and adaptedto be heated by a gaseous or liquid fuel burner at the lower endthereof.

As will be described presently, enriched absorption liquid flows fromabsorber Ilia in a path of flow which includes a conduit 65 andan innerpassage of liquid heat exchanger 66 whose upper end is connected at 61to boiler I5b at a region below the liquid surface level maintained inthe latter. To the lower end of boiler b is connected the lower end ofvapor lift tube 31a thermally connected at 66 to the heating tube Ia.Liquid of decreasing refrigerant concentration flows downwardly inboiler 15a, and liquid is raised by vapor lift action in tube 3io to theupper part of standpipe or riser 32a. Absorption liquid weak inrefrigerant passes from the lower end of standpipe 32a into the outerpassage of liquid heat exchanger 66 and thence through conduit 21a intothe upper part of absorber Ida.

Vapor for lifting absorption liquid through lift tube Sla passes fromthe upper end of standpipe 32a through a conduit 33a into the upperinclined section I5c of boiler I5b and bubbles through liquid therein,such inclined section constituting an analyzer similar to the analyzer I5a in Fig. l. The vapor generated in boiler Ib and lifting vaporentering through conduit 3 I a passes from analyzer I5c into rectier Iaand into condenser Ila in which refrigerant vapor is condensed andliquefied.

The lower end of condenser IIa is connected at 68a to vessel 35a whichis disposed about conduit 26a through which relatively cool enriched gasflows from evaporator IZc to absorber Ida. Liquid refrigerant flows fromvessel 35a through conduits lea and a and is raised in the latter to acondenser 38u,` provided with cooling ns 39a. The lifting vapor iscondensed in condenser 38a and such condensate, together with raisedliquid, is `conducted to the evaporator 12a in the same manner thatliquid is conducted from condenser 38 to evaporator I2 in Fig. l.Evaporator I2a is connected in a gas circuit which includes a gas heatexchanger 24a, only the outer end of which is seen in Fig. 6. In orderto simplify Fig. 6, the connections between evaporator I2a and gas heatexchanger 24a are not shown, it being understood that such connectionsare similar to those illustrated in Fig. 1 and described above.

The vessel a in Fig. 6 differs from the corresponding vessel 35 in Fig.1 in that it is divided by a partition 69 to form an upper space 10 anda lower space 1I. The part of vessel 35a serving as the pressure vesselforms a jacket about conduit 26a, the lower end of which terminates atan opening in partition 69. The lower space 1I constitutes the absorbervessel of the refrigeration system to an intermediate region of whichthe absorber coil Ilia is connected at 12.

The operation of the system shown in Fig. 6 is generally like thatdescribed above in connection with Fig. 1. In Fig. 6 gas enriched inrefrigerant flows from evaporator 12a through the inner passage of gasheat exchanger 24a and conduits 25a and 26a into the space 1I of vessel35a. From the upper part of such space 1I the enriched gas iiowsupwardly through absorber coil Ida countercurrent to weak absorptionliquid which enters the upper part of absorber Ida through conduit 21a.Inert gas weak in refrigerant flows from the upper part of absorber Hathrough conduit 28a and outer passage of gas heat exchanger 24a to theevaporator I2a. As previously stated, liquid refrigerant is supplied tothe evaporator from condenser 38a through conduit 40a.

Liquid refrigerant formed in condenser IIa iiows therefrom into theupper space 10 of vessel 35a and collects in the bottom part thereof. Asin the embodiment of Fig. 1, the space 10 communicates with the gascircuit through an opening 58a formed in conduit 26a.. One end ofconduit lila is connected at 13 to vessel 35a to withdraw liquidrefrigerant from the bottom of space 10. From conduit ISa liquidrefrigerant passes into conduit or lift tube 20a which is heatconductively connected at 31a to rectifier I8a. A conduit 41a similar toconduit 41 in Fig. 1 is provided for removing liquid absorbent fromspace 10 and conduits [9a and 20a'. Such conduit 41a at its upper end isconnected to rectifier Ia for conducting liquid absorbent to the latterwhich then flows by gravity in the rectier into the absorption liquidcircuit.

The conduits Isa, 20a and 41a. in Fig. 6 correspond to the conduits I5,20 and 41 in Fig. 1 and the part of the description of Fig. 1 directedto the function and operation of these members is equally applicable tothe corresponding members in Fig. 6. Although not shown, it is to beunderstood that Fig. 6 may also embody a concentration vessel like thevessel 53 in Fig. 1 and conduit connections 54 and 51 associatedtherewith.

From the absorber Ma enriched labsorption liquid ows into the lowerspace 1I of vessel 35a. which constitutes the absorber vessel. From thisvessel enriched liquid flows through conduit B5 to the boiler |51) aspreviously explained.

In Fig. 6 the condenser Ila and absorber Ma may be formed of flattenedlooped piping each having straight sections in spaced apart verticalplanes, and separate groups of cooling ns 60a may be provided for 'thestraight coil sections in each vertical plane, each n being utilizedboth for the condenser and absorber. In this manner an air shaft isformed between the spaced apart straight coil sections within which thevessel 35a is disposed. Hence, the advantages described above inconnection with Fig. 1 concerning the compact arrangement and cooling ofvessel 35, condenser II and absorber I4 are equally applicable to thesimilar compact arrangement of vessel 35h, condenser Ila and absorberIlla of Fig. 6. It should be further understood that the modiedconstructions illustrated in Figs. 2 to 5 in connection with theembodiment of Fig. 1 are also equally applicable to the embodiment ofFig. 6.

In Fig. 6 the refrigeration apparatus is fixed at a number of places 14,as by welding, to a frame 15 formed of angle members 16, 11, 18 and 19.Such frame 15 may be removably secured to a household refrigeratorcabinet at the rear insulated wall thereof so as to position theapparatus in a vertically extending space dened by the rear insulatedwall and rearwardly extendspace, due to the positioning of heatdissipating parts of the refrigeration apparatus therein, promotesupward natural draft circulation of air for cooling such heatdissipating parts which include the condenser, absorber and pressurevessel.

The embodiment of Fig. 1 lends itself to enicient air cooling becausethe absorber I4, condenser II and pressure vessel 35 provide a compactunitary construction in which the pressure vessel is contacted byupwardly flowing cooling air at substantially the same time such coolingair sweeps over the surfaces of the condenser. Further, the straightportion of the piping forming the condenser I I may form an elongatedcoil which encircles and is more or less wrapped about the pressurevessel 35, thereby tending to localize the regions at which heat isgiven up to cooling air and making more effective the induced naturaldraft circulation of air over these parts. Since the pressure vessel 35is effectively cooled, it serves as an extension of the condenser II inwhich effective condensation of refrigerant vapor takes place, therebycontributing to a compact condenser and pressure vessel construction. Itis for this reason that the condenser 38 of Fig. 1 may be omitted, ifdesired, and the arrangement of Fig, 2 employed in which vapor forlifting liquid can be returned from the upper end of lift tube orconduit to the pressure vessel 35. as shown in Fig. 2 and describedabove.

As stated above, the condenser may envelop the pressure vessel in whichcase the 'straight sections of the condenser I I are disposed in spacedapart vertical planes. Similarly, the absorber coil I4 may be formed in-a similar manner, and. by virtue of the compact arrangement of theseparts, they can be treated or considered as a single component in thefabrication of the refrigeration apparatus. This is especially importantwhen heat -dissinating members are provided on the absorber coil I4which also may be utilized as heat transfer members for the,` condenserII. Such a construction is shown in Fig. 1 in which the length of thefins 60 is approximately the same as the overall height of the condenserII and absorber I4. It is to be understood that a separate group of suchns 50 may be provided for the straight sections of the condenser II andabsorber I4 in each vertical plane of such straight sections, therebyproviding a vertically extending air shaft therebetween in which thepressure vessel 35 is disposed and subjected to vigorous cooling effectby the natural draft circulation of air induced in the manner describedabove.

This arrangement of condenser II, absorber I4 and pressure vessel 35 isespecially important in a refrigeration system of the type shown in Fig.1 in which the condenser is located below the evaporator. This is sobecause the compact condenser, absorber and pressure vessel structure islocated at a relatively low leve1 compared to the overall height of theapparatus. With such construction heat is dissipated from all of theheat emitting parts or components near the lower part lof the apparatusspace which tends to promote a driving upward force to cooling air beingcirculated by natural draft circulation. Such driving upward forceimparted to cooling air can be accentuated by closing off the open sidefof the vertically extending apparatus space previously described fromthe upper end of the cabinet down to the condenser or, if desired, to apoint immediately below the absorber. In this way a good chimney effectcan be provided to cause upward movement of air by natural draftcirculation over the heat emitting parts of the apparatus to take upheat dissipated therefrom.

In another phase of the invention special consideration is given to thestoring of enriched absorption liquid in the absorption liquid circuit.It is usually the practice to flow enriched absorption liquid from theabsorber coil to a vessel and collect liquid therein, such collectedliquid forming the upper part of a liquid column under the influence ofwhich liquid is raised to a higher level in the vapor expulsion unit.Since heat of absorption is liberated in the absorber coil, suchenriched absorption liquid collecting in the storage vessel isrelatively warm. It is customary to flow such warm absorption liquid inthermal relation with Weak absorption liquid passing from the vaporexpulsion unit to the absorber coil in a liquid heat exchanger whichconstitutes a separate part or component of the refrigeration apparatus.

In further accord with the invention a vessel E I, which is connected toreceive enriched absorption liquid from the absorber I 4 through conduit30, is enveloped in the same body 9 of insulation enveloping the vaporexpulsion unit I0 and constructed and connected in the refrigerationsystem so that the warm enriched liquid is advantageously utilized toeffect heat transfer with weak absorption liquid and generated vapor oreither of these fluids.

As seen in Fig. l, the vessel 5I for storing enriched absorption liquidis enveloped in the single body 9 of insulating material and suchenriched absorbent rises upwardly therein from the connection of conduit30 to the upper part thereof within which the horizontally extendingpipe section or analyzer I5a projects. Below the pipe section I5a ispositioned a vertically extending coil 62 whose upper end is connectedto receive weak absorption liquid from the lower part of standpipe 32through a conduit 63. Hence, weak absorption liquid is conducteddownwardly through coil 62 and heat transfer is effected between suchweak liquid and rich absorption liquid rising in vessel 6I. In addition,conduits 21 and 3I may be arranged in heat exchange 'relation at 64, asby welding, so that further counterflow heat exchange can be effectedbetween these fluids.

By way of example and without limitation, the vessel 6I may be of suchsize that it can hold from 0.75 to 2 liters of absorption solution whichmay constitute per cent or more of the entire quantity of liquidabsorbent held in the refrigeration system. In other words, the uprightvessel 6I in the immediate vicinity of the generator I0 is arranged tohold a major portion of the absorption solution circulating in thesystem. Since the enriched liquid absorbent passing from absorber I4 isrelatively warm, it will be understood that an arrangement has beenprovided whereby heat is effectively conserved within the system, theliquid in the insulated liquid body within vessel 6I being in efficientheat transfer relation with weak liquid absorbent in coil 62. Further,by projecting the analyzer ISG, into the upper part of vessel 6I belowthe liquid level therein, a compact arrangement is also provided toeffect heat transfer between enriched absorption liquid and generatedvapor in the manner previously described.

In Fig. 6 is shown a refrigeration system generally like thatillustrated in Fig. 1 in which ing parts of the lateral side walls ofthe outer metal shell of the cabinet. When the frame 15 and apparatusfixed thereto are mounted in position, the evaporator 12a is adapted tobe positioned within the thermally insulated interior of the cabinetthrough an opening in the rear insulated wall which may be closed by aninsulated closure member. Hence, the advantages described above, inconnection with the embodiment in Fig. 1 when such system is mounted ina vertically extending apparatus space like that just described, arealso realized in the embodiment of Fig. 6.

Modifications of the embodiments of the invention which have been-described and illustrated will occur to those skilled in the art, sothat it is desired not to be limited to the particular arrangements setforth. Moreover, certain features of the invention can be advantageouslyemployed independently of other features. Therefore, it is intended inthe claims to cover all those modifications and features which do notdepart from the spirit and scope of the invention.

What is claimed is:

1. In absorption refrigeration apparatus having a plurality of partsincluding an evaporator and absorber and connections therebetween forcirculation of inert gas therethrough, one of said parts functioning totransform refrigerant vapor to liquid, a pump system providing means forconducting liquid refrigerant from said one part to said evaporator byvapor lif't action under the iniiuence of a column of liquid serving asa reaction head, another of said parts providing a vessel for holdingliquid in said column which is connected to receive liquid from said onepart and in thermal exchange relation with the connection through whichrelatively -ccol inert gas flows from said evaporator to said absorber,the vapor space of said vessel being in communication with saidlast-mentioned connection, and means for draining objectionable liquidfrom said pump system comprising a connection communicating with saidpump system and with one of said parts outside said pump system.

2. Apparatus as set forth in claim 1 in which another of said partsconstitutes a rectifier, said pump system being arranged to make use ofthe heat of rectific-ation produced by said rectifier to form vapor toconduct liquid by vapor lift action, a concentration vessel in thermalexchange relation with said rectier, and connections for owingunevaporated liquid from said evaporator to said concentration vesseland for fiowing vapor from the latter to said one part to transform suchvapor to liquid.

3. Apparatus as set forth in claim 1 in which said vessel comprises partof an upright tubular member having a partition intermediate the endsthereof, the space above said partition serving as said vessel, thespace below said partition being connected to receive absorptionsolution from said absorber and serving as a part of the latter.

4. Apparatus as set forth in claim 1 in which said part functioning totransform refrigerant vapor to liquid comprises a ycondenser and saidvessel extends vertically downward below the outlet end of saidcondenser, said condenser comprising a looped coil having verticallyextending portions which are disposed alongside of and spaced from oneanother, and a separate group of fins fixed to each of said coilpo-rtions to form an air shaft within which said vessel is disposed.

5. In the art of absorption refrigeration, the

improvement ywhich `comprises heating at a first place liquid coolingagent or such agent substantially free of another liquid to form vaporfor normally raising liquid from said first place to a second place at ahigher level by vapor lift action under the iniiuence of a column ofliquid at a third place which is removed from said rst place and servesas a reaction head and from which liquid iiows by gravity toy said firstplace, and, when said other liquid having a higher boiling point thansaid cooling agent passes to said first place, employing liquid coolingagent or such agent substantially free of said other liquid to push outand displace said other liquid from said first and third places to aplace other than said second place.

6. In the art of absorption refrigeration with the aid of a systemhaving a place lat which heat is dissipated, the improvement whichcomprises making use of such dissipated heat to heat at a first placeliquid refrigerant or such liquid refrigerant substantially free ofanother higher boiling point liquid so as to form vapor for normallyraising liquid from said first place to a second place at a higher levelby vapor lift action under the influence of a column of liquid at athird place which is removed from said first place and serves as areaction head and from which liquid flows by gravity to said firstplace, and, when said other liquid passes to said first place, employingliquid refrigerant or such refrigerant substantially free of said otherliquid to push out and displace said other liquid from said first andthird places to a place other than said second place.

7. That improvement set forth in claim 6' in which heat yofrectification is employed to effect heating of liquid at -said firstplace.

8. In the art of refrigeration with the aid of an absorptionrefrigeration system in which refrigerant evaporates in the presence ofinert gas at a place of cooling, the improvement which comprises owingunevaporated refrigerant from the place `of cooling to another place ata lower level which is out of Contact with inert gas, continuouslysupplying heat to said other place during operation of the system tovaporize liquid therein, iiowing vaporized refrigerant from said otherplace to a place of condensation, flowing condensed refrigerant formedat the place of condensation to the place of cooling in a path of flowfrom a first place at one level to a second place at a higher level byvapor lift action under the influence of a column of liquid condensateat a third place which serves as a reaction head and from which suchliquid fiows to said first place, and removing absorption solution fromthe first and third places and flowing such removed solution to a placeother than said place of cooling.

9. In the art of refrigeration in which liquid cooling agent or suchagent substantially free of absorption solution is normally raised froma rst place at one level to a second place at a higher level by vaporlift action under the iniiuence of a column of liquid cooling agent at athird place which is removed from said first place and serves as areaction head and from which such liquid fiows in a path of ow to saidfirst place, the improvement which comprises removing absorptionsolution from the iirst and third places of such path of fiow at aregion thereof located substantially at or in the Vicinity of the liquidsurface level of the reaction head produced during normal lifting ofliquid cooling agent to said second place, and flowing said removedabsorption solution from said region in a path of flow to a place otherthan said second place.

l0. In the art of refrigeration with the aid of a system in which liquidis raised by vapor lift action, the improvement which comprises heatingliquid refrigerant at a first place to form vapor therein for raisingsaid liquid by vapor lift action from said rst place at one level to asecond place at a higher level with the aid of said vapor under theinfluence of a column of liquid serving as a reaction head, and, whenliquid having an appreciable concentration of liquid absorbent flows tothe rst place, producing a positive force within the system to push outsuch last-mentioned liquid therefrom to a place vother than said secondplace.

l1. In refrigeration apparatus having a plurality of parts, a pumpsystem providing means for normally raising liquid cooling agent fromone level to a higher level by vapor lift action under the influence ofa column of liquid cooling agent serving as a reaction head, said pumpsystem comprising a riser conduit which provides a passage in whichvapor cannot freely pass liquid therein and includes a heat receivingand vapor forming part at said one level, and means for drainingobjectionable liquid from said pump system comprising a connectioncommunicating with said pump system and with one of said parts outsidesaid pump system at a level which is approximately at `or in thevicinity of the liquid .Y

12. In the art of refrigeration with the aid ofY an absorptionrefrigeration system in which refrigerant evaporates in the presence ofan inert gas at a place of cooling, the improvement which comprisesilowing unevaporated refrigerant fluid from said place of cooling toanother place at a lower level which is out of contact with inert gas,conducting in a path of ow to said place of cooling liquid refrigeranthaving a small concentration of liquid absorbent and includingrefrigerant fluid from said other place, and diverting from said path ofnow to a place other than said place of cooling liquid absorbentcollecting therein and having a substantially higher boiling point thanliquid refrigerant.

13. In an air cooled absorption refrigeration apparatus having aplurality of interconnected parts providing a gas circuit including anevaporator into the upper part of which liquid refrigerant is introducedand an absorber, and a condenser having an inlet which is connected toreceive refrigerant vapor, pumping means for conducting liquidrefrigerant from said condenser upwardly against gravity to the upperpart of said evaporator which is at a higher level than the refrigerantvapor inlet of said condenser, said pumping means including a vapor lifttube for normally raising liquid refrigerant by Vapor lift action tosaid evaporator during `operation of the apparatus, structure providinga pressure vessel which is in communication with said gas circuit andconnected to said condenser and said lift tube to hold a column ofliquid therein which serves as a reaction head for lifting liquid insaid lift tube, said pressure vessel extending vertically downward belowthe outlet end of said condenser, said pressure vessel and lift tubeforming a liquid lifting system to raise liquid refrigerant to saidevaporator, conduit means for withdrawing absorption liquid from saidsystem by displacement of such liquid by liquid refrigerant flowing fromsaid condenser, said conduit means communicating with said system in amanner to drain liquid therefrom to a lower part of the apparatus from aregion at a level approximately the same or slightly above the liquidsurface level of the reaction head formed in said pressure vessel whenliquid refrigerant is normally being raised to said evaporator, saidcondenser comprising a looped coil having vertically extending portionswhich are disposed alongside of and spaced from one another, and aseparate group of fins fixed to cach of said coil portions to form anair shaft. said pressure vessel being disposed within such shaft.

WILHELM GEORG KOGEL.

References Cited in the ille of this patent UNITED STATES PATENTS-lumber Name Date 2,069,865 Ullstrand Feb. 9, 1937 2,129,982 Ashby Sept.13, 1938 2,194,505 Kogel et al Mar. 26, 194() 2,252,791 Ullstrand Aug.19, 1941 2,256,584 Bergholm Dec. 16, 1941 2,295,064 Ullstrand Sept. 8,1942 2,303,816 Brace Dec. 1, 1942 2,317,519 Coons Apr. 27, 19432,321,113 Taylor June 8, 1943 2,329,863 Thomas Sept. 21, 1943 2,336,085Gaugler Dec. 7, 1943 2,338,265 Sherwood Jan. 4, 1944 2,345,454 BraceMar. 28, 1944 2,363,434 Osborn Nov. 21, 1944 2,490,401 Bergholm Dec. 6,1949 2,529,113 Stierlin Nov. 7, 1950

